Expansion screw



FIG. 1 is a perspective view of an expansion screw showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines in the drawings illustrate portions of the expansion screw and form no part of the claimed design. 

CLAIM The ornamental design for an expansion screw, as shown and described. 